light and electricity, many tests are required on the properties of materials, such as the magnetic properties of iron that is to be used in dynamo-electric machines. All engineering is but applied physics, and a whole building has been devoted to the testing of materials used in engineering and in manufacturing, such as the strength of steel and iron, of concrete, and other materials used in construction, of thread, paper, leather and textile manufactures. It is known that the government buys all its supplies on specification, and for many of the bureaus the testing is carried on at the Bureau of Standards. In addition the Bureau has two branches, one at Pittsburgh, for testing structural materials, and one at Northampton, Pa., for testing cement, where all the cement used in the Panama Canal is tested. It is easy to see how under this rigid testing many improvements of importance to manufacturers are developed, and in this way industry is largely promoted. In fact the bureau is now of as much interest to manufacturers and engineers as it is to physicists.
I have now said enough to show the direct practical importance to the country of a laboratory in which testing, as well as research, is done, even though no teaching is done there. But when I speak of contributions to civilization I do not by any means limit myself to the increase of human comfort, and to the increasing of the production of wealth. Neither do I consider this as the main object of science, nor its chief justification, although it is one that is most easily apprehended by all intellects. Science does not consist in the observation and classification of facts that are useful in this narrow sense, but rather in the fitting of them into a great and harmonious system, that convinces us of the reasonable scheme of nature, and gives us the same esthetic pleasure that the performance of a great piece of music affords, and lifts our spirits to the contemplation of the author of that great scheme of nature, of which, however much we learn, an infinitely greater amount remains for us still to explore. It is only to those who have personally wrestled with nature in the attempt to make her yield up her secrets that this highest aspect of science is revealed. Fortunate are those who, untrammeled by practical ends or the hope of gain, can devote their lives to the calm, undisturbed questioning of nature, and such should our college professors be. It is not yet generally understood that professors should be paid such salaries that they may take this high view of their calling, without being disturbed and in a large degree prevented from fulfilling these highest duties by the struggle for existence.
I shall now, having described some of the objects and means of research in physical laboratories, attempt briefly to trace the history of one or two notable discoveries of the last quarter of a century, with the results of which at least the public is in a large measure concerned. One hundred years before the present time, almost all that was known of
